Oral care implements, such as toothbrushes, are mass-produced articles and must therefore allow cost-effective production. Toothbrushes made of a single plastic material and toothbrushes made of two plastic components, which are produced for example by a two component injection molding process, are known. In the latter case, known toothbrushes generally comprise two parts: a first part made of a hard plastic material, for example polypropylene; and a second part made of a resilient plastic material, for example a thermoplastic elastomer. Typically, the first part, which is made of the hard plastic material, forms the structural portion of the handle and has a recess or channel formed therein. This recess is filled with the resilient plastic material, thereby forming the second part which acts as a gripping surface or cover.
The hard plastic and the resilient soft plastic are selected so that they bond with one another at the surface where the two plastic parts touch. In comparison with a toothbrush made of only one plastic material, this provides greater scope for design. Since, however, the two plastic materials have to bond with one another during the injection-molding operation, there are restrictions in the selection of the plastic materials and consequently in the design of the toothbrush.
One solution to the limitation that two plastic materials must bond with one another during the injection molding operation has been introduced by which a handle can be formed by two plastics that do not chemically bond within one another during the injection molding operation but rather utilize a mechanical connection, such as by inter-fitting portions of the two plastic components or by shrinking one plastic component about the other. With respect to creating a two component toothbrush having a grip cover over a hard plastic body, this known method is limited in its design capability to a tubular sleeve that receives a cylindrical core structure within its cavity so as to circumferentially surround the entire circumference of the cylindrical core structure. This arrangement is limiting in both possible designs for the handle and the fact that the resulting handle must either be bulky or sacrifice strength.
Another oral care implement having a multi-component handle that is known in the art includes a gripping region having a thermoplastic elastomer (“TPE”) grip surface with a plurality of spaced slot openings exposing portions of a hard plastic base. This handle also includes an inclined portion and a soft TPE grip body extending through the hard plastic base of the handle to form opposite finger grips on the inclined portion of the handle. This soft grip body provides shifting of a mass centroid during use. In this construction, the handle of the oral care implement comprises three components, a hard plastic handle body, a grip cover/surface formed of a first TPE, and a grip body formed of a second TPE which is softer than the first TPE.
A need exists for an oral care implement, and method of manufacturing the same, that has a handle having greater design flexibility, is more cost-effective to mass produce, and/or affords comfort and control to the user during use.